Communication control apparatus, communication control method, program, and communication system

ABSTRACT

There is provided a communication control apparatus including an information acquisition unit that acquires information about channels, among frequency channels assigned to a primary system, available to a secondary system, a generation unit that generates a list of channels, among the channels available, recommended for a secondary usage node operating the secondary system, and a notification unit that notifies the secondary usage node of the list generated by the generation unit to allow the secondary usage node to select a channel for secondary usage.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/909,237, filed Mar. 1, 2018, which is a continuation of U.S.application Ser. No. 14/850,328, filed Sep. 10, 2015 (now U.S. Pat. No.9,942,773), which is a continuation of U.S. application Ser. No.13/981,377, filed on Jul. 24, 2013 (now U.S. Pat. No. 9,161,234), whichis the National Stage of International Application No.PCT/JP2012/053640, filed Feb. 16, 2012, which claims priority toJapanese Application No. 2011-038160, filed Feb. 24, 2011; the entirecontents of each of which are hereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a communication control apparatus, acommunication control method, a program, and a communication system.

BACKGROUND ART

As one of measures to mitigate exhaustion of frequency resources in thefuture, the discussion about secondary usage of a frequency is underway. The secondary usage of a frequency is to use a part or all of afrequency channel preferentially assigned to some system secondarily byanother system. In general, the system to which a frequency channel ispreferentially assigned is called a primary system and the system thatsecondarily uses the frequency channel is called a secondary system.

A TV white space is an example of the frequency channel discussed forsecondary usage. The TV white space refers to, among frequency channelsassigned to a TV broadcasting system as a primary system, a channel thatis not used by the TV broadcasting system depending on the region. Byreleasing the TV white space for secondary usage, efficient utilizationof frequency resources can be realized. As specifications of thewireless access method of the physical layer (PHY) and the MAC layer toenable secondary usage of the TV white space, for example, a pluralityof standard specifications like IEEE802.22, IEEE802.11af, and ECMA(European Computer Manufacturer Association)-392 (CogNea) is known.

The IEEE802.19 is currently working to allow smooth coexistence of aplurality of secondary systems using different wireless access methods.For example, Non-Patent Literature 1 below divides various functionsneeded for coexistence of secondary systems into three functionalentities of CM (Coexistence Manager), CE (Coexistence Enabler), and CDIS(Coexistence Discovery and Information Server). CM is a functionalentity that mainly makes a decision for coexistence. CE is a functionalentity to be an interface that mediates instruction transmission orinformation exchange between CM and a secondary usage node. CDIS is afunctional entity to be a server that manages information of a pluralityof secondary systems.

CITATION LIST Non-Patent Literature

Non-Patent Literature 1: “Coexistence System Description”, [online],[Searched on Feb. 14, 2011], the Internet <URL:https://mentor.ieee.org/802.19/dcn/11/19-11-0011-01-0001-coexistence-system-description.pdf>

SUMMARY OF INVENTION Technical Problem

However, how to arrange each of the above functional entities in whichapparatus constituting a system is not yet discussed. For example,depending on the position of CM, the load of signaling between CM and asecondary usage node via CE may degrade network performance. Inaddition, when, for example, CM is arranged on a secondary usage node,circumstances in which it is not suitable to select one CM as the masterCM can also be considered. Thus, if the arrangement of functionalentities is different, system models that can efficiently controlcoexistence of secondary systems are also different.

Therefore, technology according to the present disclosure is to providea communication control apparatus, a communication control method, aprogram, and a communication system that provide a control model capableof efficiently controlling coexistence of secondary systems.

Solution to Problem

According to an embodiment of the present disclosure, there is provideda communication control apparatus including an information acquisitionunit that acquires information about channels, among frequency channelsassigned to a primary system, available to a secondary system, ageneration unit that generates a list of channels, among the channelsavailable, recommended for a secondary usage node operating thesecondary system, and a notification unit that notifies the secondaryusage node of the list generated by the generation unit to allow thesecondary usage node to select a channel for secondary usage.

Further, the information acquisition unit may acquire the informationabout the channels available from a server storing information about oneor more secondary systems. The notification unit may notify the serverof the channel selected by the secondary usage node.

Further, the notification unit may further notify another communicationcontrol apparatus of the channel selected by the secondary usage node.

Further, the generation unit may generate the list in accordance with arequest from the secondary usage node.

Further, the generation unit may decide the channels recommended to thesecondary usage node in a way that interference with the primary systemcaused by the secondary system does not exceed a permissible level.

Further, the generation unit may decide the channels recommended to eachof the secondary usage nodes in a way that interference between thesecondary systems operated by each of the secondary usage nodes does notexceed a permissible level.

Further, when a central channel selection by a master control apparatusor an autonomous channel selection by the secondary usage node is notadopted, the communication control apparatus may generate the list andnotifies the secondary usage node of the list.

Further, according to another embodiment of the present disclosure,there is provided a communication control method to control secondaryusage of frequency channels including acquiring information aboutchannels, among frequency channels assigned to a primary system,available to a secondary system, generating a list of channels, amongthe channels available, recommended for a secondary usage node operatingthe secondary system, and notifying the secondary usage node of the listgenerated to allow the secondary usage node to select a channel forsecondary usage.

Further, according to another embodiment of the present disclosure,there is provided a program causing a computer that controls acommunication control apparatus controlling secondary usage of frequencychannels, to function as an information acquisition unit that acquiresinformation about channels, among frequency channels assigned to aprimary system, available to a secondary system, a generation unit thatgenerates a list of channels, among the channels available, recommendedfor a secondary usage node operating the secondary system, and anotification unit that notifies the secondary usage node of the listgenerated by the generation unit to allow the secondary usage node toselect a channel for the secondary usage.

Further, according to another embodiment of the present disclosure,there is provided a communication system including a communicationcontrol apparatus including an information acquisition unit thatacquires information about channels, among frequency channels assignedto a primary system, available to a secondary system, a generation unitthat generates a list of channels, among the channels available,recommended for a secondary usage node operating the secondary system,and a notification unit that notifies the secondary usage node of thelist generated by the generation unit, and a secondary usage node thatselects a channel for the secondary usage based on the list notifiedfrom the communication control apparatus.

Advantageous Effects of Invention

According to a communication control apparatus, a communication controlmethod, a program, and a communication system according to the presentdisclosure, a control model capable of efficiently controllingcoexistence of secondary systems is provided.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory view illustrating an overview of acommunication system according to an embodiment.

FIG. 2 is an explanatory view showing correlations among threefunctional entities to support coexistence.

FIG. 3 is an explanatory view showing a first example of arrangement ofthe functional entities.

FIG. 4 is an explanatory view showing a second example of arrangement ofthe functional entities.

FIG. 5 is an explanatory view showing a third example of arrangement ofthe functional entities.

FIG. 6 is an explanatory view showing a fourth example of arrangement ofthe functional entities.

FIG. 7 is a block diagram showing an example of the configuration ofapparatuses in a first control model.

FIG. 8 is a sequence diagram showing an example of the flow ofcommunication control processing in the first control model.

FIG. 9 is a block diagram showing an example of the configuration ofapparatuses in a second control model.

FIG. 10 is a sequence diagram showing an example of the flow ofcommunication control processing in the second control model.

FIG. 11 is a block diagram showing an example of the configuration ofapparatuses in a third control model.

FIG. 12 is a sequence diagram showing an example of the flow ofcommunication control processing in the third control model.

FIG. 13 is a flow chart showing an example of the flow an adaptiveselection of a control model.

DESCRIPTION OF EMBODIMENT

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the drawings, elements that have substantiallythe same function and structure are denoted with the same referencesigns, and repeated explanation is omitted.

“Description of Embodiment” will be described in the following order:

1. System Overview

-   -   1-1. Overall System Configuration    -   1-2. Description of Functional Entities    -   1-3. Example of Information Used for Decision-Making    -   1-4. Arrangement Example of Functional Entities

2. First Control Model

-   -   2-1. Apparatus Configuration    -   2-2. Processing Flow

3. Second Control Model

-   -   3-1. Apparatus Configuration    -   3-2. Processing Flow

4. Third Control Model

-   -   4-1. Apparatus Configuration    -   4-2. Processing Flow

5. Composite Control Model

6. Summary

<1. System Overview>

[1-1. Overall System Configuration]

FIG. 1 is an explanatory view illustrating an overview of acommunication system according to an embodiment.

Referring to FIG. 1, a primary transmitting station 10 constituting aprimary system and a plurality of primary receiving stations 12 areshown. The primary transmitting station 10 provides a primary systemservice to the primary receiving stations 12 positioned inside a servicearea 14. The primary transmitting station 10 may be, for example, abroadcasting station of TV broadcasting or a wireless base station or arelay station of a cellular communication method. When the primarytransmitting station 10 is a broadcasting station of TV broadcasting,the primary receiving station 12 is a receiver having a receivingantenna for TV broadcasting and a tuner. When the primary transmittingstation 10 is a wireless base station of a cellular communicationmethod, the primary receiving station 12 is a wireless terminaloperating according to the cellular communication method. In thedescription that follows, the primary transmitting station 10 and theprimary receiving station 12 may generically be called primary usagenodes.

The primary transmitting station 10 is connected to a data server 20positioned in a packet-based network 16. The packet-based network 16 maybe the Internet or a backbone network of a primary system. The dataserver 20 is a server apparatus having a database storing data onsecondary usage of secondary channels. A communication control apparatus30 is further connected to the data server 20. The communication controlapparatus 30 is an apparatus introduced to control coexistence among aplurality of secondary systems using frequency channels assigned to aprimary system.

In FIG. 1, a plurality of secondary usage nodes 40, 42 is further shown.The secondary usage node 40 is an apparatus that provides a secondarysystem service (hereinafter, called a secondary communication service)to the secondary usage node 42 positioned inside a service area 44 byusing a frequency channel assigned to a primary system. When the primarysystem is a TV broadcasting system, the secondary usage node 40 is alsocalled a master TVBD (TV Band Device). The secondary usage node 40 istypically has a geo-location function and a function to access thecommunication control apparatus 30. The secondary usage node 40 maydirectly be accessible to the data server 20. The secondary usage node42 is an apparatus positioned inside each of the service areas 44 to usethe secondary communication service provided by the secondary usage node40. When the primary system is a TV broadcasting system, the secondaryusage node 42 is also called a slave TVBD. In principle, the secondaryusage node 42 transmits a radio signal after obtaining permission fromthe nearby secondary usage node 40.

The secondary usage node 40 registers information about a secondarysystem with the data server 20 before starting the operation of thesecondary system. Then, the secondary usage node 40 operates thesecondary system based on control information provided from the dataserver 20. However, when a plurality of secondary systems is operated inparallel like the situation shown in FIG. 1, the risk of fatallyaffecting the primary system may be incurred due to collisions ofsignals between secondary systems or overlapping interference caused bysignals transmitted from each secondary system. Particularly, when thewireless access methods used by secondary systems are different, it isdifficult to operate the system while maintaining cooperation amongsecondary systems, further raising the above risk. Thus, the IEEE802.19is working on a mechanism to smoothly support coexistence of a pluralityof secondary systems (see Non-Patent Literature 1 described above). InIEEE802.19, various functions to support coexistence of secondarysystems are divided into three groups of functional entities of CM, CE,and CDIS (see FIG. 2).

[1-2. Description of Functional Entities]

(1) CM (Coexistence Manager)

CM is a functional entity that makes a decision for coexistence. CMacquires information about a primary system, information about availablechannels, and information about secondary systems. Sources from whichinformation is acquired by CM include CDIS, other CM, and secondaryusage nodes (accessed via CE). Based on the above information, CMdecides which frequency channel to be used by a secondary usage nodeunder the control thereof to operate the secondary system. CM mayfurther decide additional control parameters such as the maximumtransmission power, recommended wireless access method, and period ofupdating position data for each secondary usage node. Then, according todecided parameters, CM allows each secondary usage node to operate asecondary system or to reconfigure a secondary system.

(2) CE (Coexistence Enabler)

CE is a functional entity to be an interface that mediates instructiontransmission or information exchange between CM and a secondary usagenode. For example, CE converts information held by a secondary usagenode into a format that can be used by CM and transmits the convertedinformation to the CM. CE also converts an instruction about coexistenceof secondary systems from CM into a format that can be executed by asecondary usage node and transmits the converted information to thesecondary usage node.

(3) CDIS (Coexistence Discovery and Information Server) CDIS is afunctional entity to be a server that manages information of a pluralityof secondary systems. For example, CDIS collects information aboutsecondary systems from each secondary usage node via CE and CM. CDISalso collects information about the primary system and information aboutavailable channels from the data server 20. Then, CDIS stores collectedinformation in a database. The information stored by CDIS is used when adecision about coexistence is made by CM. CDIS also supports neighbordiscovery of neighbor-CM positioned near some CM. Further, CDIS may alsoselect a master CM described later.

In the embodiments described below, at least one of the above threefunctional entities is implemented in the communication controlapparatus 30 shown in FIG. 1. Only the one communication controlapparatus 30 is shown in the example of FIG. 1, but a plurality of thecommunication control apparatuses 30, each of which having at least oneof the functional entities, may be provided in the packet-based network16. A part of the functional entities may be implemented on theindividual secondary usage nodes 40. In addition, a part of thefunctional entities may also be implemented in the same apparatus as thedatabase 20.

[1-3. Example of Information Used for Decision-Making]

A decision for coexistence of secondary systems is made based mainly oninformation about the primary system, information about availablechannels, and information about secondary systems. The information aboutthe primary system includes, for example, at least one of the followinginformation:

Primary usage node position, antenna height, and transmission power

Primary system service area and guard area position

Primary system permissible interference amount

Information about available channels includes, for example, at least oneof the following information:

Channel number list

Maximum permissible transmission power for each channel

Spectrum mask

Channel classification

Parameters for interference calculation

The channel classification may be, for example, a classification of arestricted channel on which restrictions to allow lower transmissionpower than general transmission power are imposed and a normal channelon which no such restrictions are imposed. As an example, when theso-called Mode-I in the US FCC (Federal Communications Commission)regulations is Personal/Portable, the maximum transmission power of 100m[W] is permitted if neighboring channels of some channel are not usedby the primary system. Such a channel is handled as a normal channel. Onthe other hand, if a neighboring channel of some channel is used by theprimary system, the maximum transmission power is restricted to 40 m[W].Such a channel is handled as a restricted channel. Parameters forinterference calculation may include, for example, the adjacent channelleakage ratio (ACLR), fading margin, shadowing margin, protection ratio,and ACS (Adjacent Channel Selection).

The information about secondary systems includes, for example, at leastone of the following information:

Number of active nodes belonging to secondary systems

Wireless access method used by secondary systems

Required quality of secondary systems

Regulation ID and manufacturer ID of secondary usage nodes

Secondary usage node position, antenna height, and transmission power

Administrator information

The wireless access method may be represented in a number (or a listthereof) format identifying an individual wireless access method like,for example, IEEE802.11af, 11g, or 11n, IEEE802.22, IEEE802.16, andECMA-392. The regulation ID is an ID attached to each device whenauthenticated as a device that can be used for secondary usage.

[1-4. Arrangement Example of Functional Entities]

The above three functional entities may be arranged in each apparatus asshown, for example, in FIGS. 3 to 6. The arrangements of the functionalentities described here is only by way of example and other arrangementsmay also be used.

(1) First Example

In the example of FIG. 3, CDIS is arranged in a communication controlapparatus 30 a and CM is arranged in each of communication controlapparatuses 30 b, 30 c. Further, CM is arranged also on a secondaryusage node 40 d. Among these CMs, the CM in the communication controlapparatus 30 b is specified as the master CM. Other CMs become slaveCMs. Secondary usage nodes 40 a, 40 b belong to the communicationcontrol apparatus 30 b. A secondary usage node 40 c and the secondaryusage node 40 d belong to the communication control apparatus 30 c. CEis arranged on each of the secondary usage nodes 40 a, 40 b, 40 c, 40 d.Thus, each of the secondary usage nodes 40 as master devices (which aredifferent from the master CM and may be, for example, master TVBD)operating each secondary system has at least CE to interact with CM.

(2) Second example

In the example of FIG. 4, CDIS is arranged in the communication controlapparatus 30. On the other hand, CM is arranged on each of the secondaryusage nodes 40 a, 40 b, 40 c, 40 d. Among these CMs, the CM on thesecondary usage node 40 a is specified as the master CM. Other CMsbecome slave CMs. Further, CE is arranged on each of the secondary usagenodes 40 a, 40 b, 40 c, 40 d. Thus, CM may be arranged on a secondaryusage node or in a packet-based network.

(3) Third Example

In the example of FIG. 5, CDIS and CM are arranged in the communicationcontrol apparatus 30. Thus, CDIS and CM may be arranged in oneapparatus. Further, CM is arranged on the secondary usage node 40 bbelonging to the communication control apparatus 30. Each CM is neitherthe master CM nor slave CM. CE is arranged on each of the secondaryusage nodes 40 a, 40 b.

(4) Fourth Example

In the example of FIG. 6, CDIS is arranged in the communication controlapparatus 30. Further, CM is arranged on each of the secondary usagenodes 40 a, 40 b belonging to the communication control apparatus 30.Also in the example of FIG. 6, each CM is neither the master CM norslave CM. CE is arranged on each of the secondary usage nodes 40 a, 40b.

Therefore, the functional entities for coexistence of secondary systemsare arranged in various forms in a system and if the arrangement of thefunctional entities is different, system models that can efficientlycontrol coexistence of secondary systems are also different. Therefore,three control models to efficiently control coexistence of secondarysystems will be described below.

<2. First Control Model>

The first control model is a control model in which one master CM makesdecisions concentratedly. Slave CMs follow decisions made by the masterCM. The first control model is suitable for the arrangement offunctional entities as illustrated in, for example, FIG. 3.

[2-1. Apparatus Configuration]

FIG. 7 is a block diagram showing an example of the configuration ofapparatuses in the first control model. Referring to FIG. 7, thecommunication control apparatus 30 a having CDIS, the communicationcontrol apparatus 30 b having CM, and the secondary usage node 40 havingCE are shown.

(1) CDIS

The communication control apparatus 30 a includes a communication unit111, a storage unit 112, and a control unit 113.

The communication unit 111 is a communication interface for thecommunication control apparatus 30 a to communicate with otherapparatuses. Though not shown in FIG. 7, the communication unit 111 isalso connected to the data server 20 shown in FIG. 1. Communication bythe communication unit 111 may be wireless communication or wirecommunication.

The storage unit 112 stores information about the primary systemcollected by the communication control apparatus 30 a using a hard diskor a storage medium such as a semiconductor memory, information aboutavailable channels, and information about secondary systems.

The control unit 113 controls the function of the communication controlapparatus 30 a as CDIS using a processor such as a CPU (CentralProcessing Unit). For example, the control unit 113 collects informationabout secondary systems from each of the secondary usage nodes 40 via CEand CM. The control unit 113 also collects information about the primarysystem and information about available channels from the data server 20.The control unit 113 also supports neighbor discovery of neighbor-CMpositioned near some CM.

In the first control model, the control unit 113 selects one master CMfrom a plurality of CMs. For example, the control unit 113 may selectthe master CM according to at least one of the following selectioncriteria:

CM having capabilities as the master CM

Arranged closer to CDIS in a hierarchical structure of nodes

Communicable with CDIS at a higher rate

Then, the control unit 113 notifies each CM of the selection resultafter the master CM being selected.

(2) CM

The communication control apparatus 30 b includes a communication unit121, a storage unit 122, and a control unit 123.

The communication unit 121 is a communication interface for thecommunication control apparatus 30 b to communicate with otherapparatuses. Though not shown in FIG. 7, the communication unit 121 isalso connected to the data server 20 shown in FIG. 1. Communication bythe communication unit 121 may be wireless communication or wirecommunication.

The storage unit 122 stores information acquired by the communicationcontrol unit 30 b using a hard disk or a storage medium such as asemiconductor memory.

The control unit 123 controls the function of the communication controlapparatus 30 b as CM using a processor such as a CPU. More specifically,in the first control model, the control unit 123 includes an informationacquisition unit 124, a decision unit 125, and a notification unit 126.

If CM of the local apparatus is specified as the master CM, theinformation acquisition unit 124 acquires information about the primarysystem and information about channels, among frequency channels assignedto the primary system, available for secondary systems from thecommunication control apparatus 30 a having CDIS via the communicationunit 121. In addition, the information acquisition unit 124 acquiresinformation about secondary systems from the secondary usage nodes 40via the communication unit 121. The decision unit 125 decides thechannel, among available channels, to be used by each of the secondaryusage nodes 40 operating secondary systems. Decision targets heretypically include the master CM and all the active secondary usage nodes40 belonging to slave CMs. Then, the notification unit 126 notifies eachof the secondary usage nodes 40 of the channel decided by the decisionunit 125.

The decision unit 125 may decide channels to be used by each of thesecondary usage nodes 40 in such a way that the total of interferencewith the primary system caused by secondary systems does not exceed thepermissible amount of interference of the primary system based on, forexample, information acquired by the information acquisition unit 124.Alternatively, the decision unit 125 may decide channels to be used byeach of the secondary usage nodes 40 in such a way that, for example,mutual interference between secondary systems does not exceed apermissible level. The interference level between systems can becalculated based on the node position, antenna height, transmissionpower, and above parameters for interference calculation. In addition,the permissible interference level can be preset for each system orcalculated based on required quality of each system. If the normalchannel and the restricted channel can be assigned, the decision unit125 may assign the normal channel preferentially to each of thesecondary usage nodes 40. If the wireless access method that can be usedby a plurality of secondary systems supports the mesh protocol, thedecision unit 125 may form a mesh network by assigning a channel commonto the plurality of secondary systems. However, criteria for assigning achannel are not limited to the examples described here and othercriteria may also be used.

If another CM is specified as the master CM, the information acquisitionunit 124 acquires a notification of channel assignment decided by themaster CM via the communication unit 121. Then, the decision unit 125recognizes the channel to be used by the secondary usage nodes 40belonging to CM of the local apparatus as slave CM based on thenotification acquired by the information acquisition unit 124. Then, thenotification unit 126 notifies each of the secondary usage nodes 40 ofthe recognized channel.

(3) CE

The secondary usage node 40 includes a communication unit 131, a storageunit 132, and a control unit 133.

The communication unit 131 contains a communication interface for thesecondary usage node 40 to communicate with an apparatus in thepacket-based network 16 and a communication interface for the secondaryusage node 40 to operate a secondary system. Communication with thepacket-based network 16 by the communication unit 131 may be wirelesscommunication or wire communication.

The storage unit 132 stores information acquired by the secondary usagenode 40 using a hard disk or a storage medium such as a semiconductormemory.

The control unit 133 controls the function of the secondary usage node40 as CE and also controls the operation of a secondary system by thesecondary usage node 40 using a processor such as a CPU. For example,when the channel to be used for the operation of a secondary system isnotified from CM, the control unit 133 interprets the notification fromCM to recognize the notified channel. Then, the control unit 133 startsthe operation of a secondary system or reconfigures a secondary systemon the recognized channel.

[2-2. Processing Flow]

FIG. 8 is a sequence diagram showing an example of the flow ofcommunication control processing in the first control model. Referringto FIG. 8, CM first collects information about secondary systems from CEof the secondary usage nodes 40 belonging to the local apparatus (stepS102). CDIS collects information about secondary systems from each CM(steps S104, S106). CDIS also acquires information about the primarysystem and information about available channels from the data server 20.

Next, CDIS selects one master CM from a plurality of CM based on theacquired information (step S108). Next, CDIS transmits a masterselection notification for notification of the selection result of themaster CM to each CM (steps S112, S116). The CM selected as the masterCM transmits a response indicating acceptance of the selection to CDIS(step S114).

Subsequently, the master CM exchanges information used for selection ofthe channel with CDIS and slave CM (step S118). Next, the master CMdecides the channel to be used by each of the secondary usage nodes 40operating secondary systems (step S122). Then, the master CM transmits achannel notification for notification of the channel decided for each ofthe secondary usage nodes 40 to each of the secondary usage nodes 40(step S124). The channel notification is made also to the secondaryusage nodes 40 belonging to slave CM via the slave CM (step S126). Then,a response is transmitted from each of the secondary usage nodes 40 tothe master CM (steps S128, S130).

Subsequently, the master CM transmits information about the channel tobe used by each of the secondary usage nodes 40 to CDIS (step S132).Then, CDIS updates a database based on information transmitted from themaster CM (step S134).

Incidentally, in a response to CDIS from CM in step S114, CM mayindicate a rejection of the selection as the master CM. In such a case,CDIS re-selects another CM as a candidate of the master CM.

Though not shown in FIG. 8, after the notification of the masterselection from CDIS to slave CM in step S116, a response may betransmitted from the slave CM to CDIS. When responses from all slave CMsare received (or a predetermined period passes without a response), CDIScan transmit a trigger for control start to the master CM. Incidentally,the slave CM that does not respond to the notification of the masterselection within a predetermined period or the CM that rejects theselection as the master CM may be excluded from the control by themaster CM. When a trigger for control start is received from CDIS, themaster CM can notify CDIS, other CMs, and the secondary usage nodes 40that communication control processing in step S118 and thereafter willbe started. The information exchange in step S118 may be made not onlybetween the master CM and slave CM, but also between the master CM andCM excluded from the control.

<3. Second Control Model>

In the first control model, one master CM collectively decides channelsused not only by secondary usage nodes belonging to the master CM, butalso by secondary usage nodes belonging to slave CM. In this case, thereis no possibility of mutual competition of decisions by a plurality ofCMs so that the function of CM can advantageously be realized relativelyeasily. However, according to the first control model, a large amount ofinformation needed to decide channel assignment is collected in themaster CM. Thus, there is a possibility that the load of signalingbetween the master CM and other nodes degrades network performance. Inaddition, when CM is arranged on a secondary usage node, circumstancesin which it is difficult to select one CM as the master CM in terms ofperformance can also be considered. Therefore, like the second controlmodel described in this section, it is useful to transfer a part ofauthority of CM to secondary usage nodes.

[3-1. Apparatus Configuration]

FIG. 9 is a block diagram showing an example of the configuration ofapparatuses in the second control model. Referring to FIG. 9, thecommunication control apparatus 30 a having CDIS, the communicationcontrol apparatus 30 b having CM, and the secondary usage node 40 havingCE are shown.

(1) CDIS

The communication control apparatus 30 a includes the communication unit111, the storage unit 112, and a control unit 213.

The control unit 213 controls the function of the communication controlapparatus 30 a as CDIS using a processor such as a CPU. For example, thecontrol unit 213 collects information about secondary systems from eachof the secondary usage nodes 40 via CE and CM. The control unit 213 alsocollects information about the primary system and information aboutavailable channels from the data server 20. The control unit 213 alsosupports neighbor discovery of neighbor-CM positioned near some CM. Inthe second control model, the control unit 213 does not select themaster CM. Instead, a plurality of CMs operates in parallel whilecooperating with each other.

(2) CM

The communication control apparatus 30 b includes the communication unit121, the storage unit 122, and a control unit 223.

The control unit 223 controls the function of the communication controlapparatus 30 b as CM using a processor such as a CPU. More specifically,in the second control model, the control unit 223 includes aninformation acquisition unit 224, a generation unit 225, and anotification unit 226.

The information acquisition unit 224 acquires information about theprimary system and information about channels, among frequency channelsassigned to the primary system, available for secondary systems from thecommunication control apparatus 30 a having CDIS. In addition, theinformation acquisition unit 224 acquires information about secondarysystems from the secondary usage nodes 40 belonging to CM of the localapparatus.

The generation unit 225 generates a list of channels, among availablechannels, recommended for each of the secondary usage nodes 40 based oninformation acquired by the information acquisition unit 224. Thegeneration unit 225 may generate a list of recommended channels, forexample, in response to a request from the secondary usage node 40.Alternatively, a list of recommended channels may be generated wheninterference exceeding a permissible level occurs or an event such as asignal collision is detected.

The generation unit 225 may decide channels that are not used by thesecondary usage node 40 belonging to the neighbor-CM as recommendedchannels. The generation unit 225 may also decide recommended channelsin such a way that the total of interference with the primary systemcaused by secondary systems does not exceed the permissible amount ofinterference of the primary system. Alternatively, the generation unit225 may decide recommended channels in such a way that, for example,mutual interference between secondary systems does not exceed apermissible level. When compared with a case of the first control model,the permissible interference level in the second control model may be alevel that can easily be set by allowing for a margin. If the normalchannel and the restricted channel can be assigned, the generation unit225 may recommend the normal channel preferentially to each of thesecondary usage nodes 40. However, criteria for deciding recommendedchannels are not limited to the examples described here and othercriteria may also be used.

The notification unit 226 notifies each of the secondary usage nodes 40belonging to CM of the local apparatus of a list of recommended channelsgenerated by the generation unit 225 to allow each of the secondaryusage nodes 40 to select the channel for secondary usage. Thenotification unit 226 also notifies CDIS and neighbor-CM of informationabout the channel selected by each of the secondary usage nodes 40.

(3) CE

The secondary usage node 40 includes the communication unit 131, thestorage unit 132, and a control unit 233.

The control unit 233 controls the function of the secondary usage node40 as CE and also controls the operation of a secondary system by thesecondary usage node 40 using a processor such as a CPU. When a list ofrecommended channels is notified from CM, for example, the control unit233 selects the channel to be used for operation of a secondary systemfrom channels contained in the notified list. The control unit 233 mayselect the channel in consideration of a result of sensing by thesecondary usage node 40 or 42. For example, the control unit 233 mayselect the channel according to at least one of the following selectioncriteria:

The channel can satisfy required quality of a secondary system

The channel is judged to have less interference with the primary systemor other secondary systems

However, criteria for selecting a channel are not limited to theexamples described here and other criteria may also be used. When one ora plurality of channels is selected, the control unit 233 notifies CM ofthe selection result. In addition, the control unit 233 starts theoperation of a secondary system or reconfigures a secondary system onthe selected channel.

[3-2. Processing Flow]

FIG. 10 is a sequence diagram showing an example of the flow ofcommunication control processing in the second control model. Referringto FIG. 10, a cooperative control request is first transmitted from CEto CM (step S202) and a response is transmitted from CM to CE (stepS204). The communication control processing in the second control modelmay be performed by being triggered by such a request or in accordancewith detection of any other event.

After deciding to exercise cooperative control with CE, CM acquiresinformation about the primary system and information about availablechannels from CDIS (step S206). CM also collects information aboutsecondary systems from CE of the secondary usage nodes 40 belonging tothe local apparatus (step S208). CM exchanges information used fordeciding recommended channels with the neighbor-CM (step S210).

Next, CM generates a list of recommended channels listing channels,among available channels, recommended for the secondary usage node 40(step S212). Then, CM transmits the generated list of recommendedchannels to the secondary usage node 40 (step S214).

Next, the secondary usage node 40 selects the channel to be used for theoperation of a secondary system from channels contained in the list ofrecommended channels received from CM (step S220). Then, the secondaryusage node 40 notifies CM of the selected channel via CE (step S222).

Next, CM transmits information about the channel selected by thesecondary usage node 40 to CDIS (step S224). CM also transmitsinformation about the channel selected by the secondary usage node 40 tothe neighbor-CM (step S226). When the information about the selectedchannel is received, CDIS updates the database (step S228).

After the channel notification from the secondary usage node 40 to CM instep S222, CM may check whether selections are not competing, that is,an overlapping channel is selected by a plurality of the secondary usagenodes 40. If the channel selections by the plurality of the secondaryusage nodes 40 are competing, for example, CM may transmit an updatedlist of recommended channels to the secondary usage nodes 40 other thanthe secondary usage node 40 that has transmitted the channelnotification as the first node to allow the secondary usage nodes 40 tore-select the channel to be used. If channel selections are notcompeting, a notification indicating the confirmation of the selectionof the channel to be used may be transmitted from CM to the secondaryusage node 40 so that ACK is returned from each of the secondary usagenodes 40.

In the second control model, a part of the authority of CM istransferred to secondary usage nodes and CM and secondary usage nodescooperate to decide channels for the operation of secondary systems.Performance demanded from CM is thereby reduced and therefore, dependingon the arrangement of functional entities, the second control model ispreferable to the first control model. Moreover, decisions are madewithout concentrating a large amount of information on CM and therefore,the load of signaling in a network is mitigated.

<4. Third Control Model>

The third control model is a control model in which CM arranged on eachsecondary usage node in a distributed manner individually makes adecision. The third control model is suitable for the arrangement offunctional entities as illustrated in, for example, FIG. 6.

[4-1. Apparatus Configuration]

FIG. 11 is a block diagram showing an example of the configuration ofapparatuses in the third control model. Referring to FIG. 11, thecommunication control apparatus 30 having CDIS and the secondary usagenode 40 having CM and CE are shown.

(1) CDIS

The communication control apparatus 30 includes the communication unit111, the storage unit 112, and a control unit 313.

The control unit 313 controls the function of the communication controlapparatus 30 as CDIS using a processor such as a CPU. For example, thecontrol unit 313 collects information about secondary systems from eachof the secondary usage nodes 40 via CE and CM. The control unit 313 alsocollects information about the primary system and information aboutavailable channels from the data server 20. The control unit 313 alsosupports neighbor discovery of neighbor-CM positioned near some CM. Alsoin the third control model, the control unit 313 does not select themaster CM.

(2) CM/CE

The secondary usage node 40 includes the communication unit 121, thestorage unit 122, and a control unit 323.

The control unit 323 controls the function of the secondary usage node40 as CM and CE and also controls the operation of a secondary system bythe secondary usage node 40 using a processor such as a CPU. Morespecifically, in the third control model, the control unit 323 includesan information acquisition unit 324, a selection unit 325, and asecondary system controller 326.

The information acquisition unit 324 acquires information about theprimary system and information about channels, among frequency channelsassigned to the primary system, available for secondary systems from thecommunication control apparatus 30 having CDIS.

The selection unit 325 selects the channel used for the operation of asecondary system from among available channels based on informationacquired by the information acquisition unit 324. The control unit 325may select the channel in consideration of a result of sensing by thelocal apparatus or the secondary usage node 42. If, for example, achannel not used by other secondary systems is present, the selectionunit 325 may select the channel. The selection unit 325 may also selectthe channel in such a way that interference with the primary system or anearby secondary system caused by the secondary system to be operateddoes not exceed a permissible level. If a normal channel and arestricted channel are unused, the selection unit 325 may select thenormal channel preferentially. However, criteria for selecting a channelare not limited to the examples described here and other criteria mayalso be used.

When a channel is selected by the selection unit 325, the secondarysystem controller 326 starts the operation of a secondary system orreconfigures a secondary system on the selected channel. The secondarysystem controller 326 also notifies CDIS of the selection result of achannel.

[4-2. Processing Flow]

FIG. 12 is a sequence diagram showing an example of the flow ofcommunication control processing in the third control model. Referringto FIG. 12, an autonomous control request is first transmitted from CMof the secondary usage node 40 to CDIS (step S302). Next, if theautonomous control request is approved by CDIS (step S304), CM requestsCDIS to provide a channel list (step S306). Then, CDIS provides achannel list that lists available channels to CM (step S308).

Next, CM selects the channel to be used for the operation of a secondarysystem from among channels contained in the channel list provided fromCDIS (step S310). Then, CM notifies CDIS of the selected channel (stepS312). When the channel selected by CM is notified, CDIS updates thedatabase (step S314).

In the third control model, the channel for the operation of a secondarysystem is autonomously selected by CM arranged on each secondary usagenode in a distributed manner. Also in this case, performance demandedfrom each CM can be reduced. Moreover, decisions are made withoutconcentrating information about a plurality of secondary systems on oneCM and therefore, the load of signaling in a network is mitigated.

<5. Composite Control Model>

The above three control models may compositely be used depending onsystem requirements. In addition, the three control models may also beselected adaptively.

For example, some CMs in a system may desire cooperative controlaccording to the second control model or autonomous control according tothe third control model rather than central control according to thefirst control model. In such a case, a part of the system may beoperated according to the second or third control model and theremaining part may be operated according the first control model.

In addition, for example, due to an increase in the number of nodesparticipating in a system during operation of the system according tothe first control model, the load of the master CM may exceed theprocessing capacity of the master CM. In addition, the load of asecondary usage node may exceed the processing capacity of the nodewhile a system is operated according to the third control model. In suchcases, it is useful to distribute the load by shifting the control modelin operation to another control model.

FIG. 13 is a flow chart showing an example of the flow an adaptiveselection of the control model. The processing shown in FIG. 13 can berealized as processing performed CDIS, CM (for example, the master CM),or other independent functional entities.

Referring to FIG. 13, whether any CM that can operate as the master CMis present is first determined (step S402). If, for example, no CMhaving capabilities as the master CM is present in the system, all CMsreject to operate as the master CM, or none of CM is positioned inside apacket-based network, CM capable of operating as the master CM isdetermined not to be present. If CM capable of operating as the masterCM is not present, the processing proceeds to step S408. On the otherhand, if CM capable of operating as the master CM is present, theprocessing proceeds to step S404.

In step S404, the system is operated according to the first controlmodel (step S404). Then, the load of the master CM (and/or the load ofsignaling of a network) is monitored during operation of the system(step S406). If, in step S406, the monitored load is detected exceedingthe processing capacity of the master CM (or the network capacity orlimits of QoS), the processing proceeds to step S408.

In step S408, whether a secondary usage node that can autonomously becontrolled is present in the system is determined (step S408). Thedetermination here may be made based on, for example, capabilities,performance, or QoS requirements of each secondary usage node. Then, ifthe presence of a secondary usage node that can autonomously becontrolled is determined, the processing proceeds to step S410. On theother hand, if the non-presence of a secondary usage node that canautonomously be controlled is determined, the processing proceeds tostep S414.

In step S410, at least a part of the system (for example, at least onesecondary usage node that can autonomously be controlled and a group ofnodes belonging to the secondary usage node) is operated according tothe third control model (step S410). Then, the load of the secondaryusage node operated according to the third control model is monitored(step S412). In step S412, if the monitored load is detected exceedingthe processing capacity of the secondary usage node, the processingproceeds to step S414.

In step S414, at least a part of the system is operated according to thesecond control model (step S414). In the second control model, CM andthe secondary usage node are cooperatively controlled and therefore, theload on each node can be distributed.

Then, the control model applied to the system may further be changed inaccordance with various factors such as changes in the number of nodesparticipating in the system, changes in topology, and an increase ordecrease in traffic. The change of the control model signaled from CDIS,CM (for example, the master CM), or another independent functionalentity to nodes in the system.

<6. Summary>

Heretofore, the three control models to efficiently control coexistenceof secondary systems have been described in detail. According to thefirst control model, channels used by a plurality of secondary systemsare centrally decided by one master CM. Therefore, decisions by aplurality of CMs may compete. According to the second control model, thechannel used by a secondary system is cooperatively decided between CMand a secondary usage node. That is, a part of the authority of CM canbe transferred to the secondary usage node. Performance demanded from CMcan thereby be reduced. Moreover, there is no need to concentrate alarge amount of information on one CM and therefore, the load ofsignaling in a network can be mitigated. According to the third controlmodel, the channel used by a secondary system is autonomously decided byeach CM arranged in a distributed manner. Also in this case, performancedemanded from CM can be reduced and the load of signaling in a networkcan be mitigated.

Also, according to the second control model, a list of channelsrecommended for the secondary usage node is generated by CM and providedto the secondary usage nodes. Then, the channel for the operation of asecondary system is selected from the list by the secondary usage node.CDIS and neighbor-CM are notified by CM of the channel selected by thesecondary usage node. Therefore, a part of the authority of CM can betransferred to the secondary usage node while allowing a plurality ofCMs to cooperate within the framework of the functional entities ofCDIS, CM, and CE.

A sequence of control processing by each apparatus described herein maybe realized by using any of software, hardware, and a combination ofsoftware and hardware. A program constituting software is stored in, forexample, a storage medium provided inside or outside each apparatus.Then, each program is read into RAM (Random Access Memory) duringexecution and executed by a processor such as a CPU.

The preferred embodiments of the present disclosure have been describedin detail above with reference to the accompanying drawings, whilst thetechnical scope of the present disclosure is not limited to the aboveexamples, of course. A person skilled in the art may find variousalterations and modifications within the scope of the appended claims,and it should be understood that they will naturally come under thetechnical scope of the present disclosure.

REFERENCE SIGNS LIST

10, 12 Primary usage node

20 Data server

30 Communication control apparatus

40, 42 Secondary usage node

124 Information acquisition unit

125 Decision unit

126 Notification unit

224 Information acquisition unit

225 Generation unit

226 Notification unit

324 Information acquisition unit

325 Selection unit

326 Secondary usage controller

The invention claimed is:
 1. A communication control apparatuscomprising: circuitry configured to: receive a notification of a channelselected from a list of channels recommended for second communicationservice, from two or more communication devices, respectively; determinewhether the channel selected by one of the two or more communicationdevices conflicts with a channel selected by at least one of othercommunication device of the two or more communication devices; transmita response to the two or more communication devices; wherein theresponse includes acknowledgement of the selected channel, when thechannel selected by one of the two or more communication devices doesnot conflict with the channel selected by at least one of othercommunication device of the two or more communication devices, whereinthe response includes updated list of recommended channels, when thechannel selected by one of the two or more communication devicesconflicts with the channel selected by at least one of othercommunication device of the two or more communication devices.
 2. Thecommunication control apparatus according to claim 1, wherein, when thechannel selected by one of the two or more communication devicesconflicts with the channel selected by at least one of othercommunication device of the two or more communication devices, thecircuitry is further configured to transmit a notification to a firstcommunication device to allow to operate the second communicationservice, the first communication device transmitting the notification ofselected channel first to the communication control apparatus, among thetwo or more communication devices.
 3. The communication controlapparatus according to claim 2, wherein, when the channel selected byone of the two or more communication devices conflicts with the channelselected by at least one of other communication device of the two ormore communication devices, the circuitry is further configured totransmit a notification to second communication devices to re-select achannel to be used based on the updated list of recommended channels,the second communication devices being other than the firstcommunication device in the two or more communication devices.
 4. Thecommunication control apparatus according to claim 1, wherein thecircuitry is further configured to notify another communication controlapparatus of the channel selected by the two or more communicationdevices.
 5. The communication control apparatus according to claim 1,wherein the circuitry is further configured to generate the list ofchannels recommended for second communication service, based on arequest from at least one of the two or more communication devices. 6.The communication control apparatus according to claim 1, wherein thecircuitry is further configured to determine the list of channelsrecommended to the two or more communication devices in a way thatinterference with a first communication service caused by the secondcommunication service does not exceed a permissible level.
 7. Thecommunication control apparatus according to claim 1, wherein thecircuitry is further configured to determine the list of channelsrecommended to two or more communication devices in a way thatinterference among a plurality of second communication services operatedby each of the two or more communication devices does not exceed apermissible level.
 8. A communication control method comprising:receiving a notification of a channel selected from a list of channelsrecommended for second communication service, from two or morecommunication devices, respectively; determining whether the channelselected by one of the two or more communication devices conflicts witha channel selected by at least one of other communication device of thetwo or more communication devices; transmitting a response to the two ormore communication devices; wherein the response includesacknowledgement of the selected channel, when the channel selected byone of the two or more communication devices does not conflict with thechannel selected by at least one of other communication device of thetwo or more communication devices, wherein the response includes updatedlist of recommended channels, when the channel selected by one of thetwo or more communication devices conflicts with the channel selected byat least one of other communication device of the two or morecommunication devices.
 9. A communication system, comprising: two ormore communication devices; and a communication control apparatusincluding circuitry configured to: receive a notification of a channelselected from a list of channels recommended for second communicationservice, from the two or more communication devices, respectively;determine whether the channel selected by one of the two or morecommunication devices conflicts with a channel selected by at least oneof other communication device of the two or more communication devices;transmit a response to the two or more communication devices; whereinthe response includes acknowledgement of the selected channel, when thechannel selected by one of the two or more communication devices doesnot conflict with the channel selected by at least one of othercommunication device of the two or more communication devices, whereinthe response includes updated list of recommended channels, when thechannel selected by one of the two or more communication devicesconflicts with the channel selected by at least one of othercommunication device of the two or more communication devices.